[savannahz]

In the log below I did a 3rd gear pull to redline and then shifted into fourth for a few seconds. The car is running well with MHD v7.1 Stage 1+.

The hpfp numbers appear good, but the low pressure bottoms out at 50.4. This is at the end of third gear when I'm lifting off the gas pedal. The sensor reading during wot starts at around 74.5 and goes into the 60's, then 50's, the higher the rpm's get.

http://datazap.me/u/savannahz/3rd-ge...ata=1-13-20-21

Is this too low?

Thanks

[Sgop335]

Yes, 50 is getting low. Your stft are getting close to maxed out as well.

[NA55]

What type of fuel is this map designed for and what fuel are you actually using?

Fuel system seems to be strong and has a lot of room for much more boost.

[savannahz]

I'm using the MHD v7.1 93 octane map and using either BP or Chevron 93 octane fuel. I looked back at logs from January of this year, the only other ones I have, using v5 map, 93 octane, and the stft and low pressure were all much more within spec. Once the storm clears, I think I'll revert maps and do another run to see where I stand.

Originally Posted by Sgop335

Yes, 50 is getting low. Your stft are getting close to maxed out as well.

I think you're missing the bigger picture here...you're taking one random data point and not looking at the overall trend. If you analyze the pressure readings during the most important part of the pull (while the accel ped is at ~100%) you'll see that the lpfp dips to 57.4 psi just for a split second, but the entire rest of the run it's @ 60+ with no signs of issues. Long story short, as NA55 mentioned, I think the fuel system looks fine here.

The STFTs definitely are pulling out a significant amount of fuel from ~5300 rpm on though. Could this be due to actual load/boost overshooting load/boost requested (throttle closures, etc.)? Aside from that, I'm not sure what could cause STFTs to go so negative when it would appear that there are no hardware issues at play, other than the tune itself maybe..??

That's more than likely a better question for WedgePerformance though. Not sure if having "too strong" of a fuel system contributes to negative STFTs or not (random thought there, as I'm just talking out of my tailpipe at this point).

I've encountered similar logs with MHD v7.1 93 and STFTs going into the -20s and my entire fuel system from LPFP to injectors is brand new.

[135Pats]

I haven't looked at the log so grain of salt, but if the DME is pulling out a lot of fuel it's likely the tune. As a starting point reference AFR targets and the fuel scalars.

If your biggest issue is negative trims under full throttle, you can do a helluva lot worse than that. You should address it, certainly....But IMO it's not an 'oh shit' issue. If trims were pegging positive, that would be appreciably more concerning.

[savannahz]

As a follow up: I reset the first two adaptations in mhd (one was fuel and I forget the other one) to see what effect it would have on my fuel trims. As you can see in the log below, it did seem to take them from the edge of the range to normal values.

http://datazap.me/u/savannahz/septem...17-19-22-23-28

However, the gap between the two trims has widened. If you notice between 5300 - 5800 they've gone from the 2-3 acceptable gap range to 5-7. What exactly does this mean?

http://datazap.me/u/savannahz/septem...0&data=8-13-14

Thanks